Studies On The Preparation And Properties Of Modified Urushiol And Nano TiO₂ Composite Coatings

Chinese lacquer, named as "the King of Coating", is a kind of special local product in our country. Its film is hard, heat-resistant and anti-corruptive, so the unearthed lacquer wares still keep good for 7000 years. However, it has been still an important work to improve the lacquer because of its inherent drawbacks such as being corroded by alkali, baddish weatherability, low adhesion to metal and drying only at definite temperature and humidity. Therefore, take the urushiol as the foundation, develop the coating that have special abilities, not only can advance the function and characteristic of raw lacquer coating, develop it lately applied path, but also can advance the raw lacquer to make use of its additional value. Urushiol, TiO₂ and rare earth elements have their own special functions, use the chemistry method to link them to take into the research, is a very meaningful topic. This thesis in tallying up the foundation of the past work, take urushiol, TiO₂ and rare earth elements as the raw materials to have new coatings which their capabilities are excellent, and make use of the FT-IR, TEM, SEM etc. methods and test the capabilities of acid-resistant, alkali-resistant, heat-resistant, UV-light-resistant etc., investigate the relation between its structure and functions.The main contents in this thesis are as follows:(1) Titanium dioxide nanoparticles ( TiO₂ ) treated with anionic surfactant sodium dodecyl sulfate (SDS) were dispersed into urushiol acetal epoxy resin in different mass ratio to get composite paints. Composite paints were characterized by infrared spectrometry(FT-IR), transmission electron microscope(TEM), scanning electron microscope(SEM), and its mechanical properties, alkali-resistant, acid-resistant and heat-resistant abilities were measured. The results indicate that there are strong hydrogen bond reactions between urushiol acetal epoxy resin and titanium dioxide nanoparticles. And adding TiO₂ nanoparticles can increase the alkali-resistant, acid-resistant and heat-resistant abilities. Compared with the paint without nanoparticles, adding 4% or 5% TiO₂ results in 56.7% increase of the alkali-resistant ability and 50℃ increase of the highest temperature of heat-resistant respectively of nanometer composite paint.(2) The surface of nano-TiO₂ could be simply and fast modified by chemicaladsorption in saturated solution of benzoic acid and 5-sulfosalicylic acid. After surface modification, The appearance of the color of the TiO2 derivatised with 5-sulfosalicylic acid solution is primrose yellow. FT-IR was used to characterize the stucture of TiO2 being modified, their mechanical properties and UV light-resistant abilities were measured. The result indicated that the wavelength response range of T1O2 was expanded, it has obvious absorption in the region from 320 to 450 nm; at the same time, UV-light-resistant ability of the composite coating was improved obviously, after 72 hours irradiation with UV light, the luster decline degree of T1O2 derivatised with benzoic acid and 5-sulfosalicylic acid are 44.4% and 30% of blank sample separately, and their mechanism properties are still be excellent.(3) Praseodymium chloride and ytterbium chloride were synthesized with urushiol to prepare urushiol-rare earth metal chelate complex. Urushiol-rare earth metal chelate complex /nano-TiO2 composite coatings were prepared successfully by nano TiO2 modified by SDS and urushiol-rare earth chelate complex. Chemical bonds were formed between rare earth elements and the hydroxide of urushiol, at the same time there are strong hydrogen bond reactions between hydroxiede of surface of TiC>2 nanoparticles and the hydroxide of urushiol. Therefore, the mechanism properties, alkali-resistant and heat-resistant abilities of nanometer composite coatings are all increased. When the mass percentage of rare earth elements was 5%o, the alkali-resistant and heat-resistant abilities of Urushiol-Pr and Urushiol-Yb composite coatings were increasing by 27.5% and 23.8%, the heat-resistant abilities of the two kind of composite coatings were increasing by 50 °C and 50 °C. The mechanism properties of composite coatings are declined with the increasing of content of rare earth elements, and increased with the increasing of content of HO2.